A. Field of the Invention
This invention relates to the field of piezoelectric materials and particularly to materials based on the general compound Pb(Zr,Ti)O.sub.3.
B. Description of the Prior Art
The electromechanical properties of piezoelectric materials make them suitable for use in high-frequency (over 20 MH.sub.z), acoustic surface wave devices for filters (SAW filters), discriminators, and other devices. However, prior piezoelectric materials do not have the combination of properties required to provide a stable surface wave velocity with temperature and time, while still providing good piezoelectric efficiency. The prior materials have either low coupling, high temperature coefficient of resonant frequency, high hysteresis, low mechanical Q, or poor fabricability. Such lack of optimum properties severely limits the application of acoustic surface wave devices.